Perfect Devil Trigger

The Perfect Devil Trigger is an unused form that was originally set to appear in Devil May Cry 4 but the possibility of that was dubbed as impractical. It appeared to be an evolved form of Dante's normal Devil Trigger when his power increases exponentially.

Background
According to the information translated from the Art Book, the Perfect Devil Trigger's power surpasses that of his father The Dark Knight Sparda's power, this in turn allows Dante to be seemingly all powerful and nearly unbeatable as well. However, this form is disadvantageous due to the fact that Dante will eventually lose his humanity and become a feral being of rage.

The illustration of it depicts it having wings, which indicates that Dante possesses the power of flight. His tail resembles that of his trademark sword Rebellion, which also become a part of his form. No other abilities have been described, but it is possible that it possesses the same powers as Dante's Majin Form but possibly great with various other abilities in his arsenal.

Trivia

 * In the art book it is revealed that Nero was too originally have a Perfect Devil Trigger, but was meant to be seen as his complete devil form replacing his spectral Devil Trigger and to combat Dante. Neither of these said Devil Triggers have yet to be appear in the series.